1. Field of the Invention
The present invention relates to a sheet post-processing device that subjects an image formed sheet to post-processing, an image forming apparatus having the device and an error handling method for the image forming apparatus having the sheet post-processing device.
2. Description of the Related Art
Up to now, there is an image forming apparatus such as a printer having a sheet post-processing device that puts respective end portions of a plurality of sheets on which an image has been formed (printed) in order and subjects the sheets to post-processing such as stapling before discharging the sheets. There has been known a type of sheet post-processing device, which are set at a side surface on a sheet discharge port side of an image forming apparatus main body. Sheets printed in the image forming apparatus main body are sequentially supplied to the device from the discharge port. The respective end portions of the sheets are put in order, and the sheets are subjected to post-processing. And then they are discharged.
However, the above-mentioned related art suffers from the following problems.
That is, in the image forming apparatus having the sheet post-processing device according to the related art, in order to discharge and stack the sheets that have been printed at the image forming apparatus main body side in the order of pages, it is necessary to dispose a switch-back mechanism for reversing the sheets at the sheet post-processing device side, or there is such a disadvantage that sheet intervals must be made long for switching back. Also, since the sheet post-processing device is disposed next to the sheet discharge port on the side surface of the image forming apparatus main body, there are disadvantages in that not only an area where the entire apparatus is located increases but also the costs become high.
In addition, there are many sheet post-processing devices that require an additional period of time or mechanism for error handling. For example, in the case where the number of sheet materials that exceed a stapling permissible number of sheets are stacked on a staple try, a conventional sheet post-processing device requires a control means that does not allow a succeeding sheet to be transported to the sheet post-processing device, or requires a mechanism for temporarily stopping or retreating the sheets that have been already transported, in order to discharge a bundle of sheets.
The present invention has been made to solve the above-mentioned problems with the related art, and therefore an object of the present invention is to provide a sheet post-processing device having a control means that facilitates error handling operation in the case where the number of sheets exceeds a post-processing permissible number of sheets, an image forming apparatus having the device, and an error handling method therefor.
Another object of the present invention is to provide a sheet post-processing device that appropriately processes a sheet that does not need to be post-processed to improve the utility, an image forming apparatus having the device, and an error handling method therefor.
According to the present invention, there is provided a sheet post-processing device, comprising: a first sheet discharge path through which a sheet transported from an image forming apparatus is transported to sheet stacking means disposed in the image forming apparatus; first sheet discharge path open/close means which is disposed in the first sheet discharge path, and closes the first sheet discharge path to temporarily support the sheet transported from the image forming apparatus, or opens the first sheet discharge path to transport the sheet transported from the image forming apparatus to the sheet stacking means; processing means which is disposed in the first sheet discharge path and conducts post-processing with respect to the sheet temporarily supported by the first sheet discharge path open/close means; sheet discharge path change-over control means that controls sheet discharge path change-over means that changes over a discharge path, to which the sheet discharged from said image forming apparatus is discharged, to said first sheet discharge path or a second sheet discharge path through which the sheet discharged from said image forming apparatus is discharged directly to said sheet stacking means; error handling operation necessity judging means that judges whether error handling operation that should be conducted with respect to a sheet unsuitable for the post-processing by the processing means is conducted, or not; and error handling operation means that controls at least one of the first sheet discharge path open/close means and the sheet discharge path change-over means to conduct the error handling operation.
Also, a sheet post-processing device comprises: measuring means that measures the number of sheets that are temporarily supported by the first sheet discharge path open/close means; storing means that stores the number of post-processing permissible sheets N which can be post-processed in the processing means; and comparing means that compares the number of sheets M measured by the measuring means with the number of sheets N stored by the storing means, and it is preferable that the error handling operation necessity judging means judges that the error handling operation is conducted if a result made by the comparing means satisfies a relationship of M greater than N; and that the error handling means controls the first sheet discharge path open/close means so as to open the first sheet discharge path to transport the sheet temporarily supported by the first sheet discharge path open/close means to the sheet stacking means.
Also, a sheet post-processing device comprises communication means that conducts communication with the image forming apparatus, and it is preferable that when the error handling operation necessity judging means judges that the error handling operation is conducted on the basis of information on the sheets that are going to be post-processed in the processing means which is transmitted from the image forming apparatus by the communication means, the error handling means controls the sheet discharge path change-over means so as to transport the sheets transported from the image forming apparatus to the second sheet discharge path.
Also, according to the present invention, there is provided an error handling method with respect to a sheet that is not suitable for post-processing in an image forming apparatus having a sheet post-processing device that conducts the post-processing on the discharged sheet, in which the sheet post-processing device comprises: a first sheet discharge path through which the sheet transported from the image forming apparatus is transported to sheet stacking means disposed in the image forming apparatus; first sheet discharge path open/close means which is disposed in the first sheet discharge path, and closes the first sheet discharge path to temporarily support the sheet transported from the image forming apparatus, or opens the first sheet discharge path to transport the sheet transported from the image forming apparatus to the sheet stacking means; and processing means which is disposed in the first sheet discharge path and conducts post-processing with respect to the sheet temporarily supported by the first sheet discharge path open/close means; in which the image forming apparatus comprises: image forming means that forms an image on the sheet; the sheet stacking means; and sheet discharge path change-over means that changes over a discharge path, to which the sheet discharged from said image forming apparatus is discharged, to any one of the first sheet discharge path and a second sheet discharge path along which the sheet discharged from the image forming apparatus is discharged directly to the sheet stacking means; and the method comprises the steps of: judging whether the error handling operation is conducted or not; and if the error handling operation is conducted, controlling at least any one of the first sheet discharge path open/close means and the sheet discharge path change-over means to conduct the error handling operation.
Also, it is preferable that the error handling method further comprises the steps of: comparing the number of sheets M that are temporarily supported by the first sheet discharge path open/close means with the number of post-processing permissible sheets N which can be post-processed in the processing means; judging that the error handling operation is conducted if a relationship of M greater than N is satisfied; and if the error handling operation is conducted, opening the first sheet discharge path to transport the sheets temporarily supported by the first sheet discharge path open/close means to the sheet stacking means.
Also, it is preferable that the error handling method in which information on the sheets that are going to be post-processed in the sheet processing means from the image forming apparatus to the sheet post-processing device; and if it is judged that the error handling operation is conducted on the basis of the sheet information, and controlling the sheet discharge path change-over means so as to guide the sheets transported from the image forming apparatus to the second sheet discharge path.